But apparently I’m not always getting to the pixel shader and it stops in the vertex for some reason. (I have modified the pixel shader to output always a red pixel, so I know when it goes through).

xShadowMapLight is the Matrix containing all the transformations from the lights point of view. Apparently the problem is in mul(vPos, xShadowMapLight); cause if I change the matrix for anIdentity one the shader gets to the pixel one.

But apparently I’m not always getting to the pixel shader and it stops in the vertex for some reason. (I have modified the pixel shader to output always a red pixel, so I know when it goes through).

Are You sure about that?
It will only make red the object's you want to render (say, teapot for instance), everything else will be 'clear' color, since there's no object in that place, there's no need to 'pixel shader' it.

What happens now is that object is being culled (unless you set cull mode to none).
1st parameter is camera position, 2nd is LookAt, if you swap them(I believe You wanted to set the camera to look at your object) it might work